In general, battery shells are manufactured of a cold band electrolytically coated with multiple layers. Document EP 0 629 009 B1 describes a cold band as well as a method for producing cold band electrolytically plated with nickel that is characterized by a favorable behavior during a subsequent drawing and ironing process. In order to improve the effective contact surface between the inner side of the battery shell and the cathode material, a hard coating of a nickel layer is deposited on the side of the cold band that will later form the inner side of the battery shell. During the drawing and ironing process, cracks form in this layer resulting in an enlargement of the contact surface.
A similar material is described in document EP 0 809 307 A2. The side of the band material that will later form the inner side of the battery shell is coated with a hard material layer, whereas the other side—which will later form the outer side of the battery shell—is coated with a relatively soft metal layer. To achieve a hard metal coating, this document proposes electroplating process with an alloy on the nickel basis. Document EP 0 809 307 A2 indicates various examples of the hardness of thus produced alloys. It also mentions the possibility to add organic ingredients to the galvanic bath; however, no indication regarding the hardness properties of layers produced with these baths is made. During the subsequent forming of the metal sheet into battery shells, brittle fractures are supposed to form in the electrolytically deposited hard alloy coating which results in an enlarged surface and, therefore, reduced electrical contact resistance between the cathode substance of the battery and the inner surface of the battery shell.
In general, the use of organic ingredients in galvanic bath has been known for a long time as documented, e.g., by U.S. Pat. No. 2,026,718 from 1936. This document describes the addition of aromatic sulfonic acids to the galvanic bath for the purpose of achieving a glossy layer.
The use of organic ingredients in galvanic nickel, cobalt, and nickel-cobalt baths for producing an improved cold band for the manufacturing of battery shells has also been known. So, e.g., document patent DE 19 53 707 A1 describes a procedure, during which layers of nickel, cobalt or of their alloys are deposited after an unsaturated, organic substance such as butyne diol has been added to the electrolyte. This document proposes deposition with inert anodes in a halogen-free bath at a current density of 83.8 A/dm2, where the process is controlled in such a manner as to avoid brittle deposits.
Finally, it is known from the state of art how to deposit cobalt from a galvanic bath with the aid of organic substances in order to form, e.g., ferromagnetic layers for data carriers (see, e.g., U.S. Pat. No. 4,756,816).